1. Field of the Invention
The present invention relates to high strength, chemical resistant particulate solids which are particularly suitable for use in treatments carried out in subterranean formations penetrated by well bores.
2. Description of the Prior Art
Particulate solids of various kinds, and particularly sand, are utilized routinely in carrying out production stimulation treatments in subterranean formations penetrated by well bores. For example, particulate solids are used for forming gravel packs adjacent the well bores, for propping open fractures formed in the subterranean formations, as structural fillers in cement compositions utilized in the well bores and formations, etc. The formation of a gravel pack adjacent a well bore penetrating a producing formation causes migrating solids from produced fluids to be screened out of the fluids thereby preventing plugging of flow passageways, damage to tubular goods and other equipment, etc. In carrying out treatments in subterranean formations whereby fractures are created in the formations to create flow channels therein, particular solid propping agents are commonly placed in the fractures to prevent their closure after fracturing fluid pressure reduction. A variety of other treatments and procedures are carried out in well bores and subterranean formations penetrated thereby using cement compositions which include particulate solid structural fillers.
In most of the applications for particulate solids in well bores and subterranean formations, the particulate solids are subjected to high overburden pressures and high temperatures which cause the particulate solids to be crushed and/or rapidly chemically deteriorated. For example, propping agents utilized in deep wells are often crushed by the high overburden pressures exerted thereon causing partial closure of the fractures which reduces produced fluid flow therethrough. The mixture of crushed and non-crushed propping agent remaining in the fractures has a greatly reduced permeability which results in an additional reduction in fracture flow capacity and hydrocarbon production.
Propping agent and gravel pack solids placed in relatively deep wells are subjected to increased aqueous hydrolysis deterioration at the high temperatures encountered, especially in the presence of steam. Flaws and weakened segments in the particulate solid surfaces such as microfractures and pinholes accelerate such aqueous hydrolytic deterioration.
Particulate solids utilized heretofore tend to craze and/or fragment during shipment and/or placement whereby the solids become more rounded and fines are accumulated therewith. This in turn results in reduced solids interface permeabilities and flow properties.
Thus, there is a need for particulate solids which have increased resistance to structural and chemical deterioration in high temperature environments. By the present invention, such high strength, chemical resistant particulate solids are provided as well as methods of forming and using the solids.